Honey, I know what it's like when things are bad, so bad.
Instead of doing it today, maybe do everything you can to get some support and help, or even just find some hope elsewhere away from that. The option for suicide remains still though.
You could use the time to talk to your mum about how bad you feel and get her and anyone else to help you get help.
If you kill yourself she will feel so guilty she didn't/couldn't help, she will be broken and miss you.
Have you read the loved and lost forum? Maybe you should take a look.
You know that she loves you and will miss you. Is it fair to put her through that? She will suffer for the rest of her life, yet what you are feeling is something that can change. Do you not owe it to her to fight as hard as you can?
Why don't you come into chat and see if you can spend some time in there. Or feel free to PM me if you want.
Keep fighting honey, if not for yourself, then for your mum